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High-Power High-Efficiency Photodiode for Advanced LIGO

LIGO-G010359-00-Z

David Jackrel

Ph.D. Candidate- Dept. of Materials Science & Eng.

Advisor- Dr. James S. Harris

August 14th, 2001

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Outline

Introduction Photodiode Specifications Device Structure & Materials

Experimental Results DC Response RF Response

Development Plan InGaAs GaInNAs

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Photodiode Specifications?

Parameter LIGO I Advanced LIGO

Steady-State Power 0.6 W 1~10 W

Operating Frequency 29 MHz 100 kHz

~ 180 MHzQuantum Efficiency 80% 90%

Detector Design

Bank of 6(+) PDs 1 PD

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P-I-N Device Characteristics

Large E-field in I- region

Depletion Width Width of I- region

RC time constant

Tuned to a specific

1

IW

IsJ

Js

WAKC

CR

/0

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Heterojunction Band Gap Diagram

= 1.064m h = 1.17eV

Absorption occurs in i-region

InAlAs Optically transparent to 1.06m radiation

N-layer:

In.22Al.78As

Eg2=1.8eV

P-layer:

In.22Al.78As

Eg2=1.8eV

I-layer:

In.22Ga.78As

Eg1=1.1eV

n-

i-

p-

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Rear-Illuminated PD Advantages

Conventional PD Adv. LIGO Rear-Illuminated PD

High Power High Speed Linear

Response

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InGaAs/GaAs PD Structure

•MBE

•GaAs Substrate

•InGaAs for i-layer

•InAlAs for the n- and p- layers

•Graded Buffer layer

•AR coating & Au/Pt contacts

2 m

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III-V Lattice Constants and Band Gaps

InAlAs and InGaAs well lattice matched

InAlAs much wider band gap

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TEM Images of Confined Dislocations

Device Layers:

-few dislocations

Graded Buffer:

-many dislocations

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Nd:YAG (NPRO) PD Test Setup

NPRO

(800mW)

PDPower

Meter

Power

Control

RF Amplitude

Modulator

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Quantum Efficiency: #673

Avg. Quantum Efficiency v Reverse Biasy = 0.0045e-0.7534x

R2 = 0.9808

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%

-8 -7 -6 -5 -4 -3 -2 -1

Bias (V)

QE

(%

)

30%Loss

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QE: Power & Bias Effects

#673 Edge, Popt=1.00mW, 2.57mW, 5.18mW

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

-7 -6 -5 -4 -3 -2 -1 0

V (Volts)

QE

(%

)

QE (%) 5.18mW

QE (%) 2.57mW

QE (%) 1.00mW

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DC Response Linearity: #673

Photocurrent, Vb = -6.5Vy = 0.5729x - 0.0931

R2 = 0.9993

0

5

10

15

20

25

0 5 10 15 20 25 30 35 40

P optical (mW)

I ph

(m

A)

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RF Response: 3dB Bandwidth

~4MHz, 3dB-Bandwidth

~5nF Capacitance

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C-V Characteristics (#673)

depletion width 1.44 m ~2.16m

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InGaAs Development Plan

Goals: by Sept. 2002…

90% QE

Thin substrates to 50m-100m

Maximize Bandwidth

Optimize illuminated area

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GaInNAs Lattice-Matched to GaAs

GaInNAs- Adv LIGO

InGaAs- LIGO I PD

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Conclusion

Introduction Photodiode Specifications Device Structure & Materials

InGaAs RI PIN PD

Experimental Results DC Response

70% QE RF Response

4MHz 3-dB Bandwidth

Development Plan InGaAs GaInNAs